A young couple were the victims of an unprovoked attack by a trio of thugs on a train travelling to Dartford via Woolwich.
British Transport Police officers have released CCTV images of three people they want to speak to over the assault.
A 22-year-old woman and 21-year-old man got on the 9.56pm service to Dartford at Charing Cross before a group boarded the service at either Waterloo East or London Bridge and sat close by.
A short time later on the evening of April 5, the two were physically assaulted by three members of the group in what PC Jason Weston-Collinson called a “violent and sustained attack” which meant both victims had to be hospitalised.
They got off at Woolwich Arsenal and police are still trying to establish where their attackers left the train.
PC Weston-Collinson said: “This was a nasty assault which left the victims badly hurt and, understandably, very upset.
“I am determined to catch those responsible and bring them to justice.”
Anyone with information is asked to contact British Transport Police on 0800 40 50 40, or text 61016, quoting reference SSUB/B4 of 11/06/2014.
Information can also be passed anonymously to Crimestoppers on 0800 555 111.